code: def _diff_head_to_index(
      repo: "Repo", head: str = "HEAD", **kwargs: Any
  ) -> Dict[str, List[str]]:
      index = repo.index.data["repo"]
  
      with repo.switch(head):
          head_index = repo.index.data["repo"]
  
      with ui.progress(
          desc="Calculating diff between head/index",
          unit="entry",
      ) as pb:
          return _diff(
              head_index, index, callback=pb.as_callback(), **kwargs
          )
  
file_path: dvc/dvc/repo/data.py
imports: import os
  import posixpath
  from typing import TYPE_CHECKING, Any, Dict, Iterable, List, TypedDict, Union
  from dvc.fs.callbacks import DEFAULT_CALLBACK
  from dvc.ui import ui
label_desc: Use image node_id 7 for calling a global function with example usage: _diff_head_to_index(repo, head) and returns: _diff